/Engine/Source/Runtime/Slate/Public/Framework/Notifications/NotificationManager.h
Gets all the windows that represent notifications
an array of windows that contain notifications.
void GetWindows ( [TArray](API\Runtime\Core\Containers\TArray)< [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWindow](API\Runtime\SlateCore\Widgets\SWindow) > > & OutWindows ) const